UNWINDING OF DOUBLE-STRANDED DNA HELIX BY DEHYDRATION
UNWINDING OF DOUBLE-STRANDED DNA HELIX BY DEHYDRATION
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DOI：
10.1073/pnas.78.5.2838
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发表时间：
1981-01-01
期刊：
影响因子：
--
通讯作者：
KAKEFUDA, T
中科院分区：
文献类型：
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作者：
LEE, CH;MIZUSAWA, H;KAKEFUDA, T
响应于脱水的双链DNA螺旋的构象变化进行了研究，通过监测，通过琼脂糖凝胶电泳，连接数的共价闭合的环状DNA产生的线性DNA在不同的有机溶剂的存在下，或在不同的温度下连接。DNA螺旋在加入某些有机溶剂或温度升高时解旋。在实验条件下观察到的构象变化是一个连续的过程，响应于有机溶剂的浓度。DNA螺旋的解旋1连接的Δ H恒定为Δ H。12.2 .+-. 0.4 kcal/mol（1 kcal = 4.184 kJ）;相应的Δ S和d（Δ S）/dn为2nkR和2kR，其中n是DNA的相对当量连接数（对于解旋，指Δ S = 0的状态），R是气体常数，k等于1117/碱基对数目。解旋i个连接的Δ H、Δ S和d（Δ S）/dn是i × n。12.2 kcal/mol，2inkR和2ikR。d（Δ S）/dn与k一样，与DNA中碱基对的数目成反比。不同链长的双链DNA具有平均Δ S = 35 cal/mol·cm-1。在实验条件下解旋1连接的K;这对应于127 ±。14个碱基对/相对连接。
Conformational changes of the double-stranded DNA helix in response to dehydration were investigated by monitoring, by agarose gel electrophoresis, the linking number of covalently closed circular DNA generated by ligation of linear DNA in the presence of different organic solvents or at different temperatures. The DNA helix unwinds upon addition of certain organic solvents or elevation of temperature. The conformational change observed under the experimental conditions is a continuous process in response to the organic solvent concentration. The .DELTA.H of unwinding 1 linking of the DNA helix is constant at .apprx. 12.2 .+-. 0.4 kcal/mol (1 kcal = 4.184 kJ); the corresponding .DELTA.S and d(.DELTA.S)/dn are 2nkR and 2kR, in which n is the relative equivalent linking number (referred to the state of .DELTA.S = 0 for unwinding) of the DNA, R is the gas constant, and k is equal to 1117/number of base pairs. The .DELTA.H, .DELTA.S, and d(.DELTA.S)/dn for unwinding i linkings are i .times. 12.2 kcal/mol, 2inkR, and 2ikR, respectively. d(.DELTA.S)/dn, like k, is inversely proportional to the number of base pairs in DNA. Double-stranded DNA of different chain lengths have average .DELTA.S = 35 cal/mol .cntdot. K for unwinding 1 linking under the experimental conditions; this corresponds to 127 .+-. 14 base pairs/relative linking.